Counting Unit Cubes
Measure volumes by counting unit cubes using cubic cm, cubic in, cubic ft, and other units
What a learner can do afterwards
- Count unit cubes in a 3D diagram to determine volume in cm³
- Measure the volume of a small container by filling it with centimetre cubes
- Express a measured volume using the correct cubic unit notation
1 · Read
A unit cube is a cube that is exactly 1 unit long, 1 unit wide, and 1 unit tall. If the unit is a centimetre, its volume is 1 cubic centimetre, written 1 cm³. To find the volume of a bigger shape, count how many unit cubes it takes to build it completely. If the cubes are 1 inch on each side, write the volume in cubic inches.
Ali stacks centimetre cubes into a box shape: the bottom layer has 3 rows of 3 cubes, and the top layer matches it. Layer 1 has 9 cubes, layer 2 has 9 more. 9 + 9 = 18. Some cubes are hidden inside the stack, but they still count. The volume is 18 cm³.
Always match the unit to the cubes you counted. If the cubes are 1 inch on each side, write your answer in cubic inches (in³), not cm³.
Volume is the number of unit cubes it takes to fill a shape, hidden ones included, written with the matching cubic unit.
2 · Watch
Take it off screen
Where it sits
Learn first
This opens up
Where this leads
15 questions wait behind this lesson, each with its answer explained. Every answer feeds the sky: stars light as they are learned, and dim when it is time to come back.